Most chiral metamaterials demonstrated so far are made of three-dimensional (3D) metallic nanostructures [1]}, [2]}, [3]}, [4]}, [5]}, [6]}.
However, the complexity of the associated fabrication technology and optical absorption have hindered their application. Although all-dielectric chiral metamaterials have been recenlty demonstrated[6]}, two-dimensional (2D) or planar metamaterials - i.e. MSs - are highly attractive due to compatibility with planar fabrication technologies. Despite a lower chiro-optical response due to inherent reflection symmetry, planar structures sustaining Fano resonances can exhibit strong non-reciprocal CD due to modal interference[8]}.
Thus, the recent insurgence of dielectric nanostructures and MSs enabled the realization of lossless planar structures with strong chiro-optical effects[9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}, [19]}.
